Pulmonary Embolism

Diagnosis

• Although the majority of PE originates in the proximal deep veins of the leg, only 25-50% will have clinically-evident DVT at time of PE diagnosis

• Provoking factors:

  • Active malignancy

  • Surgery (especially orthopedic)

  • Hospitalization

  • Air travel >8h

  • Hormone use/pregnancy

  • 50% unprovoked

• Symptoms

  • Sudden onset dyspnea

  • Pleuritic chest pain

  • Syncope

• Signs

  • Tachypnea, hypoxemia

  • Tachycardia, hypotension, RV dysfunction (distended jugular veins)

  • EKG (S1Q3T3)

• Signs and symptoms of DVT

Clinical Decision Rules

• Determine pre-test probability with Wells' Criteria

  • If low-pretest

    • Rule-out with PERC rule (excluded active cancer, thrombophilia, betablocker use, leg amputations, morbid obesity where leg swelling not easily determined)

      • Age ≥50

      • HR ≥100

      • SaO2 on RA <95%

      • Unilateral leg swelling

      • Hemoptysis

      • Recent surgery (≤4w requiring GA) or trauma 

      • Prior PE or DVT

      • Hormone use (OCP, hormone replacement)

    • If low-pretest but cannot rule out with PERC, consider D-dimer

      • Negative D-dimer rules out PE

      • Positive D-dimer warrants further testing

        • Consider age>50 → use age x 10 as the cutoff

        • Consider adjusting threshold to clinical probability using YEARS Criteria, especially in pregnancy, consider PE ruled out

          • If 1 to 3 YEARS and D-dimer < 500 ng/mL

          • if no YEARS and D-dimer < 1000 ng/mL

  • If high pre-test

    • CT PA directly 

    • V/Q in patients with normal CXR and no significant lung disease 

      • Consider in renal failure, contrast allergy, young patients with normal CXR, pregnant women

Treatment

• Treat high pre-test while awaiting diagnostic imaging (unless high risk bleeding - eg, active bleeding or immediate postop)

  • Treatment can be withheld for 4h for intermediate, and 24h for low pre-test probability

• Risk stratify with PESI model (outpatient vs. inpatient)

  • Discharge asymptomatic patients or low clinical severity score

    • DOAC preferred

      • Rivaroxaban 15mg BID x 21d then 20mg PO daily (can consider decrease to 10mg PO daily after 6 months based on EINSTEIN CHOICE study)

      • Apixaban 10mg BID x 7d then 5mg PO BID (can consider decrease to 2.5mg PO BID after 6 months based on AMPLIFY Extend study)

  • Hospitalize patients with symptomatic and elevated clinical severity score, including elevated biomarkers (lactate) and/or RV dysfunction, incipient cardiopulmonary failure, or cardiopulmonary failure characterized by persistent hypotension

    • Consider advanced therapies (systemic thrombolysis, catheter-based thrombolysis, mechanical thrombectomy, and surgical embolectomy)

      • Full dose thrombolysis in cardiac arrest, consider half-dose in peri-arrest or high-risk PE.

        • Alteplase (tPA): 1mg/kg IV up to max 100mg. Half-dose alteplase: 0.5mg/kg, up to max 50mg. 10-20mg bolus with the rest given as an infusion over 2hrs.

          • In cardiac arrest, give 50mg IV push over 15 minutes, repeat 50mg IV bolus if still arrested (it ROSC give remaining 50mg IV bolus over 1 hour).

        • Tenecteplase (TNK): 0.5mg/kg IV push up to max 50mg. Half-dose tenecteplase: 0.25mg/kg given as a single bolus, up to max 25mg.

    • LMWH preferred (note: LMWH is not a contraindication for thrombolytics)

• Anticoagulation for three months

  • Consider IVC if cannot be anticoagulated due to risks

• Screen for chronic thromboembolic pulmonary disease (CTEPD) at every visit for 1 year

  • Ask about PE-related symptoms and functional limitations